Elmi A A, West C P
Agricultural Research Station, Virginia State Univ., Petersburg, VA 23806, USA.
Department of Agronomy, 276 Altheimer Dr., University of Arkansas, Fayetteville, AR 72704, USA.
New Phytol. 1995 Sep;131(1):61-67. doi: 10.1111/j.1469-8137.1995.tb03055.x.
Presence of the endophytic; fungus Acremonium coenophialum Morgan-Jones and Gams in tall fescue (Festuca artuidinacea- Sehreb.) enhances host persistence in drought-prone environments. However, the physiological mechanism is not well understood. We investigated the influence of endophyte infection and water deficit on osmotic adjustment, stomatal conductance, tiller survival and leaf elongation rate of genotype GA87-122 and cv. Kentucky-31 (KY31) of tall fescue. Plants were grown in a greenhouse in pots containing fine-silty topsoil (experiment 1) or sand (experiment 2). In expt 1, endophyte-infected (EI) and endophyte-free (EF) isolines of GA87-122 were exposed to two drought preconditioning cycles, after which all pots were re-watered and osmotic adjustment determined. Osmotic adjustment was -0.46 and -0.51 MPa in El leaf blades and tiller bases and -0.29 and -0.13 MPa in EF leaf blades and tiller bases, respectively. In expt 2, EI and EF GA87-122 and KY31 Mere exposed to severe drought after two preconditioning cycles, then re-watered. During the second preconditioning drying cycle of KY31, stomatal conductance tended to be lower in EI than in EF plants, but the difference was significant (P⩽ 0-05) only at two sampling times. Shoot tissues osmotically adjusted 0.17-0.31 MPa more in EI than in EF plants. Tiller survival and leaf elongation rates were higher (P⩽ 0.05) in preconditioned EI than in EF plants. Basal-zone osmotic adjustment was correlated with tiller survival rate in GA87-122 and KY31 (r = 0.87, P⩽ 0.01 for both). Enhanced osmotic adjustment in the meristematic and growing zone might account far improved survival of tillers by facilitating protection of the apical meristem.
内生真菌Acremonium coenophialum Morgan-Jones和Gams存在于高羊茅（Festuca arundinacea Schreb.）中，可增强宿主在干旱频发环境中的持久性。然而，其生理机制尚不清楚。我们研究了内生真菌感染和水分亏缺对高羊茅基因型GA87-122和品种肯塔基31（KY31）渗透调节、气孔导度、分蘖存活和叶片伸长率的影响。植株种植在温室中装有细粉质表土的花盆里（实验1）或沙子里（实验2）。在实验1中，GA87-122的内生真菌感染（EI）和无内生真菌（EF）同基因系经历了两个干旱预处理周期，之后所有花盆重新浇水并测定渗透调节。EI叶片和分蘖基部的渗透调节分别为-0.46和-0.51 MPa，EF叶片和分蘖基部的渗透调节分别为-0.29和-0.13 MPa。在实验2中，EI和EF的GA87-122以及KY31在经历两个预处理周期后遭受严重干旱，然后重新浇水。在KY31的第二个预处理干燥周期中，EI植株的气孔导度往往低于EF植株，但仅在两个采样时间差异显著（P≤0.05）。地上部组织EI植株比EF植株渗透调节多0.17 - 0.31 MPa。预处理后的EI植株分蘖存活率和叶片伸长率高于EF植株（P≤0.05）。GA87-122和KY31的基部区域渗透调节与分蘖存活率相关（两者r = 0.87，P≤0.01）。分生组织和生长区域渗透调节增强可能是通过促进顶端分生组织的保护来提高分蘖存活率。
